The advantages associated with low friction bearings are well known to a multitude of varied industries. High-speed applications with DN (dynamic number) values over 1,000,000 are common place for turbomachinery. These high-speed applications, owing to the fact that rotor imbalance force increases as a square function of rotor speed, require damping. Without damping, transmitted forces through the system would cause many well-known problems such as noise, fretting, loosening of joints, and overall reduced service life. Further, the bearings themselves would have unacceptable life. For these reasons, turbomachinery bearings are not hard mounted within their housings. The skilled rotordynamics design engineer spends the majority of his/her life managing these forces, especially those forces encountered as the rotor goes through its natural frequencies, commonly referred to as “critical speeds”.
Most turbochargers that employ a low friction rolling element bearing use two angular contact ball bearings, with each accepting the thrust load in a given axial direction, that are joined together in what is commonly referred to as a “cartridge”. In a cylindrical coordinate system a bearing may be defined with respect to axial, radial and azimuthal dimensions. Within a bearing housing, referred to as housing in subsequent text, a cartridge is located axially and azimuthally via one or more mechanisms. For proper functioning, some movement can occur in a radial direction along a radial line typically defined by an azimuthal locating mechanism.
Conventional bearing cartridge and housing assemblies typically rely on an axial thrust load pin to locate the cartridge axially and azimuthally within a housing. Such pins have a limited ability to align the cartridge in a housing and receive most of the thrust load. Consequently, axial thrust load pins can raise serious wear and misalignment issues.
Overall, an industry need exists for rolling element bearings and/or housings that allow for better alignment and/or reduced wear. Various exemplary bearing cartridges and housings presented herein address such issues and optionally other issues.